Though many companies are interested in noise prediction, not many studies have been performed in the area of noise prediction.
In order to control fan noise, one should be able to control performance and noise and accordingly shape of the fan needs to be modified. Low noise fan manufacturers should know how to perform experiments and how to analyze as well.
So far, any analysis method for centrifugal fan noise has not been reported because it requires not only understanding of complicated techniques but also combination of complicated techniques.